India’s Supreme Court ruled Wednesday that sex with an underage wife constitutes rape, in a landmark ruling that campaigners say could affect millions of girls.

The decision overturned a previous clause that permitted men to have sex with a married girl as young as 15, the Indian Express reports.

India’s age of consent is 18 and child marriage is illegal, but the practice persists in many parts of the country. According to Girls Not Brides — a coalition of NGOs working to end child marriage — 47% of Indian girls are married by the age of 18.

India’s Supreme Court Rules Sex With Child Brides Is Rape – Time